title: Influence of thyrotropin-releasing hormone on the secretion of thyrotropin in neonatal rats.
abstract: Two hours after the ip administration of TRH antiserum, no change in serum TSH concentration was observed in the rat from birth through day 5 of life. Under the same conditions, a significant reduction in serum TSH was observed in 7- to 14-day-old rats. Similarly, in neonatal hypothyroidism, TSH levels did not change in 1-day-old rats, whereas a significant decrease was observed on day 7. The administration of synthetic TRH during the neonatal period induced a significant increase of serum TSH in the newborn; however, TSH release by the pituitary gland increased progressively from days 3-10. Immunoreactive TRH was undetectable in the serum of newborn rats. Adult levels were reached when the rats were 10 days old. It is concluded that neonatal pituitary-thyroid function in the rat is not physiologically dependent upon TRH secretion, although synthetic TRH is able to stimulate the secretion of TSH at birth.
mesh_terms: D000375:Aging; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D005260:Female; D007037:Hypothyroidism / Q000503:physiopathology; D051381:Rats; D013972:Thyrotropin / Q000097:blood / Q000378:metabolism*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
chemical_list: D013973:Thyrotropin-Releasing Hormone; D013972:Thyrotropin